These bookends are made from Opal Stone originating from Zimbabwe.
Opal stone is famous for its milky light coloured greens and smooth texture. It is also known as Opalite to the locals and is mined at Chiweshe, two hours north of Harare. This stone is one of the favourites of carvers, as it is not as hard as Spring stone and other serpentines, but still polishes to a high finish.
As with most stones mined for the purpose of sculpting, Opalite is mined without the use of power tools.